Calibration apparatus



FIG. 1 is a front perspective view of a calibration apparatus, showing our new design;

FIG. 2 is a back perspective view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a right side elevation view thereof;

FIG. 5 is a back elevation view thereof;

FIG. 6 is a left side elevation view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

The broken lines immediately adjacent to the claim, represent the bounds of the claim while all other broken lines are directed to environment; the broken lines form no part of the claimed design. 

CLAIM We claim the ornamental design for a calibration apparatus, as shown and described. 